In what is being billed as a speech to prepare members for the election campaign ahead, Willie Rennie is expected to tell them gains can be made on every regional list and the party can also win new seats.
The latest polling for The Scotsman by Savanta ComRes saw the Scottish Liberal Democrats gain just one constituency seat while the regional list vote saw them poll just 6 per cent of votes which, as in the 2016 election, could see them return just one additional MSP.
The Scotsman understands the party is targeting the Caithness, Sutherland & Ross constituency seat, which is being contested by children’s minister Maree Todd, after incumbent SNP MSP Gail Ross decided not to stand again.
It is also confident in retaining the four constituencies it currently holds, and the campaign will frame Mr Rennie as the more popular face of pro-union politics in comparison to the Scottish Conservative’s new leader Douglas Ross.
Mr Rennie is expected to say: "The Liberal Democrats can make the difference at the next election. We can make gains in every region. We can win new seats.
"The Conservatives can’t. They have replaced Ruth Davidson, who was popular, with Boris Johnson’s choice of leader who is not. Their tide is running away. They are set to lose seats. Every poll says so.
"Anas Sarwar will take time to find his feet. So Labour are unlikely to make the necessary progress on their own. And the Greens will always back the SNP when they need them.”
He will add: "The Liberal Democrats, with our plan to put recovery first, are ready to win more seats.
"Our gains will make the difference between a government that can do whatever it wants, however damaging, and a government that has to listen. I am ready.
“With a decade of experience leading the Liberal Democrats in Scotland. Rebuilding our party with wins in Holyrood, Westminster, Europe and by-elections. Working with others to win in Parliament on education on mental health and on the budget.
"I am ready to lead the Liberal Democrats to the gains that will put recovery first."
However, his message was dismissed by the SNP, with a spokesperson saying voters could not “trust a word the Liberal Democrats say, they sold their soul to the Tories before and they'll do it again when they need to deny the people of Scotland their right to choose their own future”.
The spokesperson added: “They have ditched their policy of re-joining the EU, against the expressed will of the people of Scotland.
"Willie Rennie joins the likes of Boris Johnson in denying the people of Scotland their democratic will to hold a post-pandemic referendum – there's nothing liberal nor democratic about that position.
"The election in May will be about Scotland's right to choose and it will be the people of Scotland who will decide their future – not Willie Rennie.”